'archaeon' originates from Greek, specifically the word 'arkhaios' (ἄρχαιος), where 'arkhaios' meant 'ancient' and the suffix '-on' was a neuter noun ending used in scientific names.

'archaeon' changed from New Latin/modern scientific usage (related to the taxon name 'Archaea' coined in the 20th century) and eventually became the modern English scientific noun 'archaeon'.

Initially it meant 'ancient one' (from Greek), but over time it evolved into its current meaning of 'a single-celled microorganism of the domain Archaea'.